In a semiconductor memory device, a global input/output line serves as a data transmission line for transmitting data between an input/output pin and a memory core during a read or write operation.
If the input/output line has a long length, great load is applied thereto so that the swing of the data signal, which is transmitted through the global input/output line, is prolonged during the read and write operation, thereby deteriorating the operational margin.
In order to solve this problem, a repeater is provided at a middle part of the global input/output line to improve the operational speed by distributing the load. In addition, it is necessary to transmit data in one direction from the global input/output line connected to the repeater according to the read or write operation relative to a bank.
FIG. 1 is a circuit view of a repeater provided in a global input/output line according to the related art.
As shown in FIG. 1, the conventional repeater of the global input/output line has a simple inverter logic.
In the case of transmitting data from A to B, if a transmission direction control signal CTRL has a high level, a control signal CTRLB has a low level. At this time, NMOSs of pull-down drivers N1 and N2 are turned ON and PMOSs of pull-up drivers P1 and P2 are also turned ON, so that data are transmitted from A to B. In addition, NMOSs of pull-down drivers N3 and N4 are turned OFF and PMOSs of pull-up drivers P3 and P4 are also turned OFF, so that data transmission from B to A is blocked.
In the case of transmitting data from B to A, if a transmission direction control signal CTRL has a low level, a control signal CTRLB has a high level. At this time, NMOSs of pull-down drivers N3 and N4 are turned ON and PMOSs of pull-up drivers P3 and P4 are also turned ON, so that data are transmitted from B to A. In addition, NMOSs of pull-down drivers N1 and N2 located in an “A” area are turned OFF and PMOSs of pull-up drivers P1 and P2 are also turned OFF, so that data transmission from A to B is blocked.
That is, the data can be transmitted from A to B or vice versa according to circumstances, so that the global input/output line can transmit the data signals in bi-direction.
However, such a repeater has a simple inverter structure, so it may cause great current consumption and increase delay time. That is, since the PMOS of the pull-up driver P2 and the NMOS of the pull-down driver N2 as well as the PMOS of pull-up driver P3 and the NMOS of the pull-down driver N3 are aligned in series in the repeater, driving force of a MOS transistor is reduced by a half.